Active memory sharing (AMS) is a memory virtualization technology that allows multiple partitions to share a pool of physical memory. This is designed to increase system memory utilization, thereby enabling you to realize a cost benefit by reducing the amount of physical memory required.
Active memory expansion (AME) is a feature available on commercially available computer systems. AME allows a partition to expand its memory up to a given factor. This memory expansion is obtained using in-memory data compression. AME relies on the real-time compression of data stored in memory to increase the amount of available memory. When AME is enabled, the operating system compresses a portion of the real memory, generating two pools: (i) compressed; and (ii) uncompressed memory. Both AME and AMS are distinct, but compatible, features related to memory virtualization.
Steal time is the percentage of time a virtual CPU waits for a real CPU while the hypervisor is servicing another virtual processor. CPU time, or CPU usage, can be reported for: (i) each thread; (ii) each process; and/or (iii) the entire system. Moreover, depending on what exactly the CPU was doing, the reported values may be subdivided into distinct categories, including: (i) user time (the amount of time the CPU was busy executing code in user space); (ii) system time (the amount of time the CPU was busy executing code in kernel space, if this value is reported for a thread or process, then it represents the amount of time the kernel was doing work on behalf of the executing context, for example, after a thread issued a system call); (iii) idle time (for the whole system only) (the amount of time the CPU was not busy, or, otherwise, the amount of time it executed the system idle process, that is, idle time actually measures unused CPU capacity); and/or (iv) steal time (for the whole system only) (on virtualized hardware, is the amount of time the operating system wanted to execute, but was not allowed to by the hypervisor).